Polyurethane Fibers Research Articles

Enhanced antimicrobial property of polyurethane fibers bearing nanoparticles of polyacrylic acid-grafted oleyl amine and zwitterion

Enhanced antimicrobial property of polyurethane fibers bearing nanoparticles of polyacrylic acid-grafted oleyl amine and zwitterion

Synthesis of novel reactive disperse dyes comprising α-phenyl diazo ester groups for polyurethane fiber dyeing

A new molecular design of dyes comprising diazo groups was proposed to address the severe staining problem of polyurethane (PU) fibers dyed with disperse dyes. Nine reactive disperse dyes containing α-phenyl diazo ester as the reactive group were designed and synthesized, and their structures were characterized using nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and infrared spectroscopy. The absorption and thermal properties of the nine dyes were also investigated. PU fibers were dyed with these dyes, and the corresponding dyeing and fixing processes were optimized. PU fibers treated using a simple heating process exhibited excellent fixation performance, which was confirmed through studying their fixation, migration, and fastness properties. PU fibers dyed with dyes containing one diazo group exhibited fixation values of 50.6%–75.8%, which were considerably increased to 83.9%–92.9% when dyes with two diazo groups were used. These high fixation values hindered the migration of the dye molecules, effectively reducing their staining on other fibers. Therefore, the dyed PU fibers exhibited excellent color fastnesses to soaping, rubbing, and sublimation. The reaction mechanism between the dye and fiber was proposed based on a model reaction experiment and theoretical analysis. The results indicated that the N–H bond of the PU macromolecule was the main reaction site, on which carbene intermediates reacted with the fiber through an insertion reaction.

Reversibly crosslinked polyurethane fibres from sugar-based 5-chloromethylfurfural: Synthesis, fibre-spinning and fibre-to-fibre recycling.

The development of recyclable crosslinked thermosetting fibres is a challenging research topic. In the present work, we have designed and synthesized polyurethane fibres from fructose-derived 5-chloromethylfurfural (CMF) and lignin-derived monomeric phenols. The greenhouse gas emissions associated with the production of CMF showed comparable results to that of 5-hydroxymethylfurfural (HMF), a high potential sugar-based platform molecule. The wet-spun biobased polyurethane fibres produced could be conveniently crosslinked using Diels-Alder chemistry to effectively enhance the glass transition temperature and mechanical properties. At a mildly elevated temperature (140 °C), the chemically crosslinked fibres could be effectively de-crosslinked, which enabled complete separation from a mixture with poly(ethylene terephthalate) (PET) and cotton fibres. These results outline a potential strategy to design and fabricate new biobased fibres with reversible crosslinking, which may enable fibre-to-fibre recycling.

A Soft, Fatigue‐free, and Self‐healable Ionic Elastomer via the Synergy of Skin‐like Assembly and Bouligand Structure

AbstractSoft ionic elastomers that are self‐healable, fatigue‐free, and environment‐tolerant are ideal structural and sensing materials for artificial prosthetics, soft electronics, and robotics to survive unpredictable service conditions. However, most synthetic strategies failed to unite rapid healing, fatigue resistance, and environmental robustness, limited by their singular compositional/structural designs. Here, we present a soft, tough, fatigue‐resistant, and self‐healable ionic elastomer (STFSI elastomer), which fuses skin‐like binary assembly and Bouligand helicoidal structure into a composite of thermoplastic polyurethane (TPU) fibers and a supramolecular ionic biopolymer. The interlocked binary assembly enables skin‐like softness, high stretchability, and strain‐adaptive stiffening through a matrix‐to‐scaffold stress transfer. The Bouligand structure contributes to superhigh fracture toughness (101.6 kJ m−2) and fatigue resistance (4937 J m−2) via mechanical toughening by interlayer slipping and twisted crack propagation path. Besides, the STFSI elastomer is self‐healable through a “bridging” method and environment‐tolerant (−20 °C, strong acid/alkali, saltwater). To demonstrate the versatile structural and sensing applications, we showcase a safety cushion with efficient damping and suppressed rebounding, and a robotic sensor with excellent fatigue crack tolerance and instant sensation recovery upon cutting‐off damage. Our presented synthetic strategy is generalizable to other fiber‐reinforced tough polymers for applications involving demanding mechanical/environmental conditions.

A Soft, Fatigue-free, and Self-healable Ionic Elastomer via the Synergy of Skin-like Assembly and Bouligand Structure.

Soft ionic elastomers that are self-healable, fatigue-free, and environment-tolerant are ideal structural and sensing materials for artificial prosthetics, soft electronics, and robotics to survive unpredictable service conditions. However, most synthetic strategies failed to unite rapid healing, fatigue resistance, and environmental robustness, limited by their singular compositional/structural designs. Here, we present a soft, tough, fatigue-resistant, and self-healable ionic elastomer (STFSI elastomer), which fuses skin-like binary assembly and Bouligand helicoidal structure into a composite of thermoplastic polyurethane (TPU) fibers and a supramolecular ionic biopolymer. The interlocked binary assembly enables skin-like softness, high stretchability, and strain-adaptive stiffening through a matrix-to-scaffold stress transfer. The Bouligand structure contributes to superhigh fracture toughness (101.6 kJ m-2) and fatigue resistance (4937 J m-2) via mechanical toughening by interlayer slipping and twisted crack propagation path. Besides, the STFSI elastomer is self-healable through a "bridging" method and environment-tolerant (-20 °C, strong acid/alkali, saltwater). To demonstrate the versatile structural and sensing applications, we showcase a safety cushion with efficient damping and suppressed rebounding, and a robotic sensor with excellent fatigue crack tolerance and instant sensation recovery upon cutting-off damage. Our presented synthetic strategy is generalizable to other fiber-reinforced tough polymers for applications involving demanding mechanical/environmental conditions.

Quantitative study of triboemission kinetics from polymer fiber-reinforced mortar paving blocks: Unravelling the dynamics of nanoparticle aerosol release

Triboemission of nanoparticle aerosols from construction materials is a growing concern due to its potential impact on air quality and human health. In this study, we investigated the effect of aggregation of polyurethane fibers (PUFs) proceeding from waste on the kinetics of triboemission in cement mortars. A quantitative methodology was employed to assess the deposition rate, particle size distribution, and emissivity for the aerosols within the particle aerodynamic diameter range of 10–400 nm. The triboemission properties were correlated with the pore structure, morphology and tribochemical transformations of the particles and worn surfaces. Our results highlight the intricate influence of PUF aggregation on the kinetics of triboemission in cement mortars through both direct and indirect mechanisms and provide valuable insights into the mechanisms governing triboemission in construction materials.

Research progress of electrospinning polyurethane fiber in the field of biomedical tissue engineering

Polyurethane materials have good biocompatibility, blood compatibility, mechanical properties, fatigue resistance and processability, and have always been highly valued as medical materials. Polyurethane fibers prepared by electrostatic spinning technology can better mimic the structure of natural extracellular matrices (ECMs), and seed cells can adhere and proliferate better to meet the requirements of tissue repair and reconstruction. The purpose of this review is to present the research progress of electrostatically spun polyurethane fibers in bone tissue engineering, skin tissue engineering, neural tissue engineering, vascular tissue engineering and cardiac tissue engineering, so that researchers can understand the practical applications of electrostatically spun polyurethane fibers in tissue engineering and regenerative medicine.

Enhancing the dyeability of polyurethane fibers by introducing protonated tertiary amine groups

Traditional polyurethane fibers (CPUF) are widely used in the preparation of blend clothing in order to improve the elasticity and comfort of fabrics. However, there has been a problem of low acid dye adsorption for CPUF, resulting in light hue of dyed CPUF. In this work, a poly (HMDI-BHOPA) was prepared with dicyclohexylmethane 4,4′-diisocyanate (HMDI) and 1,4-(2-hydroxyethyl) piperazine (BHOPA), and then added into the CPUF spinning solution for the preparation of modified polyurethane fibers (BPUFs) through dry-spinning technology. Tertiary amine groups were introduced after the addition of poly (HMDI-BHOPA), which could be protonated at acidic conditions to form binding sites for acid dyes, further enhancing the adsorption capacity of the fibers. Nuclear magnetic resonance spectroscopy (1H and 13C NMR) was used to confirm the structure of poly (HMDI-BHOPA). The results of differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) demonstrated that the addition of poly (HMDI-BHOPA) had little effect on the glass transition temperature and thermal stability of BPUFs. The addition of poly (HMDI-BHOPA) affected the ordered arrangement of hard segments and reduced crystallization enthalpy of hard and soft segments in polyurethane. Hence, the elastic recovery of BPUFs showed little change, and the elongation at break and break strength decreased compared to CPUF. Zeta potential testing results showed that BPUFs was protonated under acidic conditions. Dyeing results proved the enhancement of dyeability of BPUFs. The dyeing kinetics and thermodynamics of acid dyes on BPUFs were studied to investigate the dyeing mechanism. From the dyeing kinetics results, both CPUF and BPUFs fitted Elovich model. From dyeing thermodynamics results, Langmuir model showed a better applicability for BPUFs at a low pH and temperature condition, while Freundlich model fitted better for CPUF.

Enhanced electromagnetic interference shielding via surface-bound molecules and synergistically amplified polarization and triboelectrification

Achieving high-performance electromagnetic interference (EMI) shielding materials with ultra-low reflectivity, minimal volume, and light weight is challenging. This study addresses this by introducing a nanofiber (NF)-based structure composed of MXene nanoflakes and ferroelectric barium titanate oxide (BTO) nanoparticles embedded within polyurethane (PU) fibers, and surface-bound branched polyethyleneimine (PEI(b)) on the NFs. This design enhances the flexibility and lightness of the EMI shielding materials while effectively minimizing reflectivity. A key approach in this study is the functionalization of the NFs with branched polyethyleneimine (PEI(b)), which reduces reflectivity and enhances EMI shielding effectiveness (SE). The surface-bound molecules increase the effective surface area, improving the absorption efficiency of incident electromagnetic waves without adding weight or volume. Additionally, the surface-bound PEI(b) molecules synergistically enhance the polarization of the embedded BTO nanoparticles and amplify the triboelectric charging effect, crucial for achieving ultra-low reflectivity and high EMI SE. Combining the optimized composite NF design with these enhancement methods, this study achieves significant advancements in EMI SE, reaching an EMI SE of 72 dB, an absolute EMI SE (SSEt) of 28,460 dB·cm²g−1, and a reflectivity of 0.09, all without increasing weight or volume. This approach exemplifies how the strategic application of surface-bound molecules can enhance EMI shielding effectiveness and achieve ultra-low reflectivity through the effective expansion of the absorption surface and synergistic enhancement of piezoelectric and triboelectric effects.

Water-efficient evaporative cooling by sunlight-reflective radiative-cooling nanofibers

Evaporative cooling, which has the highest potential for energy transfer, is not sustainable without sufficient water. Here we present the membrane that can be used to protect the moisture from unnecessary evaporation. The membrane is composed of nanofiber non-woven fabric that is breathable and has high solar reflectance and high infrared emissivity for water-efficient evaporative cooling applications. The membrane prevents moisture from evaporating unnecessarily by blocking solar absorption and efficient thermal emission. Specifically, the membrane is composed of ∼400 nm diameter polyurethane fiber, which has a high MIE scattering effect on solar radiation (∼2500 nm wavelength), resulting in over 95% solar reflectance as well as over 95% of total infrared (IR) emissivity and IR transmittance at 50 g/m2 of membrane. In addition, it has sufficient breathability of over 16 mg•cm2•hr that the maximum evaporative cooling is about 100 W/m2. Twice the cooling time and 3 °C cooler surface by tandem of radiative cooling were confirmed in outdoor test of wet fabric covered with nanofiber membrane compared to wet fabric without membrane. This scalable and flexible membrane is applicable where the thermal cooling without energy consumption is required for net-zero energy consumption.

All-Fiber Flexible Electrochemical Sensor for Wearable Glucose Monitoring.

Wearable sensors, specifically microneedle sensors based on electrochemical methods, have expanded extensively with recent technological advances. Today's wearable electrochemical sensors present specific challenges: they show significant modulus disparities with skin tissue, implying possible discomfort in vivo, especially over extended wear periods or on sensitive skin areas. The sensors, primarily based on polyethylene terephthalate (PET) or polyimide (PI) substrates, might also cause pressure or unease during insertion due to the skin's irregular deformation. To address these constraints, we developed an innovative, wearable, all-fiber-structured electrochemical sensor. Our composite sensor incorporates polyurethane (PU) fibers prepared via electrospinning as electrode substrates to achieve excellent adaptability. Electrospun PU nanofiber films with gold layers shaped via thermal evaporation are used as base electrodes with exemplary conductivity and electrochemical catalytic attributes. To achieve glucose monitoring, gold nanofibers functionalized by gold nanoflakes (AuNFs) and glucose oxidase (GOx) serve as the working electrode, while Pt nanofibers and Ag/AgCl nanofibers serve as the counter and reference electrode. The acrylamide-sodium alginate double-network hydrogel synthesized on electrospun PU fibers serves as the adhesive and substance-transferring layer between the electrodes. The all-fiber electrochemical sensor is assembled layer-by-layer to form a robust structure. Given the stretchability of PU nanofibers coupled with a high specific surface area, the manufactured porous microneedle glucose sensor exhibits enhanced stretchability, superior sensitivity at 31.94 μA (lg(mM))-1 cm-2, a broad detection range (1-30 mM), and a significantly low detection limit (1 mM, S/N = 3), as well as satisfactory biocompatibility. Therefore, the novel electrochemical microneedle design is well-suited for wearable or even implantable continuous monitoring applications, thereby showing promising significant potential within the global arena of wearable medical technology.

Unraveling the Impact of Boron Nitride and Silicon Nitride Nanoparticles on Thermoplastic Polyurethane Fibers and Mats for Advanced Heat Management.

The urgent challenges posed by the energy crisis, alongside the heat dissipation of advanced electronics, have embarked on a rising demand for the development of highly thermally conductive polymer composites. Electrospun composite mats, known for their flexibility, permeability, high concentration and orientational degree of conductive fillers, stand out as one of the prime candidates for addressing this need. This study explores the efficacy of boron nitride (BN) and its potential alternative, silicon nitride (SiN) nanoparticles, in enhancing the thermal performance of the electrospun composite thermoplastic polyurethane (TPU) fibers and mats. The 3D reconstructed models obtained from FIB-SEM imaging provided valuable insights into the morphology of the composite fibers, aiding the interpretation of the measured thermal performance through scanning thermal microscopy for the individual composite fibers and infrared thermography for the composite mats. Notably, we found that TPU-SiN fibers exhibit superior heat conduction compared to TPU-BN fibers, with up to a 6 °C higher surface temperature observed in mats coated on copper pipes. Our results underscore the crucial role of arrangement of nanoparticles and fiber morphology in improving heat conduction in the electrospun composites. Moreover, SiN nanoparticles are introduced as a more suitable filler for heat conduction enhancement of electrospun TPU fibers and mats, suggesting immense potential for smart textiles and thermal management applications.

Linear Film Strain Sensors with Nanosphere‐on‐Fiber Hetero‐Modulus Microstructure for Human‐Bionic Finger Interfacing

AbstractStretchable film strain sensors show potential applications in healthcare and human‐machine interfacing, while poor signal linearity restricts their practical applications owing to inaccurate and instable strain indication. Signal sensitivity and linearity can be improved via constructing hetero‐modulus microstructure on elastomeric substrate to some extent, though it is challenging to construct hetero‐structure with distinct modulus differences for electrical signal linearity modulation over a wide strain range. Herein, a simple strategy is proposed to tune signal sensitivity, linearity, and detection range of stretchable strain sensors by adjusting the distribution of rigid polystyrene (PS) nanospheres coated on electrospun thermoplastic polyurethane (TPU) fiber mats. Heterostructure characteristics can be controlled by spray coating times of PS nanospheres, which are immobilized onto the fiber mats by weak swelling of TPU and the linking layer of reduced graphene oxide (rGO) between TPU and PS induced by hydrogen bonding and π–π stacking. Relatively, the sensors with moderate spray coating times of PS nanospheres show balanced signal sensitivity and linearity over a strain range of 0–80%, as well as fast response to tensile strain and good signal reproducibility. Such elastomeric film strain sensors can be used for monitoring physiological activities and interfacing human hand and bionic fingers.

In vitro and in vivo evaluation of biohybrid tissue-engineered vascular grafts with transformative 1H/19F MRI traceable scaffolds

Biohybrid tissue-engineered vascular grafts (TEVGs) promise long-term durability due to their ability to adapt to hosts' needs. However, the latter calls for sensitive non-invasive imaging approaches to longitudinally monitor their functionality, integrity, and positioning. Here, we present an imaging approach comprising the labeling of non-degradable and degradable TEVGs' components for their in vitro and in vivo monitoring by hybrid 1H/19F MRI. TEVGs (inner diameter 1.5 mm) consisted of biodegradable poly(lactic-co-glycolic acid) (PLGA) fibers passively incorporating superparamagnetic iron oxide nanoparticles (SPIONs), non-degradable polyvinylidene fluoride scaffolds labeled with highly fluorinated thermoplastic polyurethane (19F-TPU) fibers, a smooth muscle cells containing fibrin blend, and endothelial cells. 1H/19F MRI of TEVGs in bioreactors, and after subcutaneous and infrarenal implantation in rats, revealed that PLGA degradation could be faithfully monitored by the decreasing SPIONs signal. The 19F signal of 19F-TPU remained constant over weeks. PLGA degradation was compensated by cells’ collagen and α-smooth-muscle-actin deposition. Interestingly, only TEVGs implanted on the abdominal aorta contained elastin. XTT and histology proved that our imaging markers did not influence extracellular matrix deposition and host immune reaction. This concept of non-invasive longitudinal assessment of cardiovascular implants using 1H/19F MRI might be applicable to various biohybrid tissue-engineered implants, facilitating their clinical translation.

Multi-modal heat rechargeable phase change composites based on MXene coated core-sheath fiber strategy

In order to maintain the human body temperature within a comfortable range in harsh environments, flexible and wearable thermal management fabrics that can combine energy storage and multi-modal heat recharging ability are urgently needed. Here, a strategy of coaxial electrospinning and spray coating was proposed to prepare the MXene-coated core-sheath phase change fibers to satisfy the above requirement. The hierarchical structure endows the composite film with phase change energy storage and photo/electro-thermal multi-modal heat charging performance. Specifically, the encapsulated paraffin wax (PW) in flexible polyurethane (PU) fibers has a high enthalpy value of 91.7 J/g, meanwhile, the flexible film exhibits excellent photo-thermal performance conversion capability (up to 40 °C under the irradiation intensity of 30 mW/cm2) and electro-thermal conversion capability (up to 40 °C at the voltage of 1.5 V) at extremely low MXene loading (0.23 mg cm−2), which endows the MXene/PU@PW (MPP) ability of “heat recharging” by low light power density or low voltage. The multifunctional fabrics with phase change function and multi-modal heat recharging capacity exhibit great potential application in the design of wearable personal thermal management.

Post‐modification of azo dyes using an α‐phenyl diazo ester for improving the colour fixation properties of polyurethane fibre

AbstractColour fastness of polyurethane fibre dyed with conventional disperse dyes is always poor owing to the insufficient affinity between fibres and dyes. Thus, three novel azo dyes containing an α‐phenyl diazo ester moiety were designed in this study. The dyes were synthesised through two‐step post‐modification of a hydroxylated azo benzene chromophore. All three dyes were characterised using proton and carbon nuclear magnetic resonance, high‐resolution mass spectrometry and infrared spectrometry. The ultraviolet‐visible absorption and thermal properties of the dyes were also studied. Fixation properties of these dyes on polyurethane fibre were examined using samples dyed using a non‐aqueous dyeing method. Practicality of these dyes, that is colour depth, fixation value, colour fastness and dye migration degree, was further verified on fibre dyed via an aqueous dyeing method. Finally, the mechanical properties of the dyed polyurethane fibre were explored.

Reduced Graphene-Oxide-Doped Elastic Biodegradable Polyurethane Fibers for Cardiomyocyte Maturation.

Conductive biomaterials offer promising solutions to enhance the maturity of cultured cardiomyocytes. While the conventional culture of cardiomyocytes on nonconductive materials leads to more immature characteristics, conductive microenvironments have the potential to support sarcomere development, gap junction formation, and beating of cardiomyocytes in vitro. In this study, we systematically investigated the behaviors of cardiomyocytes on aligned electrospun fibrous membranes composed of elastic and biodegradable polyurethane (PU) doped with varying concentrations of reduced graphene oxide (rGO). Compared to PU and PU-4%rGO membranes, the PU-10%rGO membrane exhibited the highest conductivity, approaching levels close to those of native heart tissue. The PU-rGO membranes retained anisotropic viscoelastic behavior similar to that of the porcine left ventricle and a superior tensile strength. Neonatal rat cardiomyocytes (NRCMs) and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) on the PU-rGO membranes displayed enhanced maturation with cell alignment and enhanced sarcomere structure and gap junction formation with PU-10%rGO having the most improved sarcomere structure and CX-43 presence. hiPSC-CMs on the PU-rGO membranes exhibited a uniform and synchronous beating pattern compared with that on PU membranes. Overall, PU-10%rGO exhibited the best performance for cardiomyocyte maturation. The conductive PU-rGO membranes provide a promising matrix for in vitro cardiomyocyte culture with promoted cell maturation/functionality and the potential for cardiac disease treatment.

Ultralow shrinkage polyimide hybrid aerogel composite enhanced with organic fibers for thermal protection

AbstractPolyimide (PI) aerogels possess a rather potential in thermal protection material for aircraft, owing to their low thermal conductivity, high thermal stability, and low bulk density. However, the large shrinkage of pure PI aerogels is still a challenge in the complete preparation process. Herein, a kind of PI hybrid aerogel composite was prepared successfully by introducing polyurethane fiber as the reinforcing agent. The aerogel composite could realize the enhancement for the pure PI aerogels from a micro/macroscopic perspective, ultimately ensuring the ultralow shrinkage rate of 3.52%. Due to the inhibition of the shrinkage characteristic, the aerogel composite obtained achieved excellent thermal insulation, especially retaining a low temperature of 40.7°C despite the hot surface temperature reached up to 150°C. Besides, the lightweight low‐density, exceptional flame resistance, and self‐extinguishing properties were reflected from PI hybrid aerogel composite constructed, including the outstanding hydrophobic feature (water contact angle of 120°). The PI hybrid aerogel composite as prepared may be used for the thermal management of aircraft in a great measure, illustrating the feasible strategy of fabricating PI‐based aerogel composites.

Polyurethane nanofibers incorporated magnesium hydroxide followed by hydrothermal treatment using chitosan and silver nanoparticles to improve the biological properties

AbstractThe study aimed to explore the potential of magnesium hydroxide (Mg[OH]₂) nanoparticles (NPs) incorporated into polyurethane (PU) fibers, which were further coated with chitosan and silver (Ag) NPs. The hydrothermal approach was adopted to add the properties of chitosan and Ag NPs to the as‐spun fibers. These samples were characterized by field emission scanning electron microscope (FE‐SEM), EDS, Fourier transform infrared spectroscopy, thermogravimetric analysis, and contact angle measurements. The diameter of concocted fibers was found to be 0.79 ± 0.31 μm to 2.5 ± 0.9 μm. The presence of Mg(OH)2 decreased the fiber diameter from 2.05 ± 1.2 μm to 0.79 ± 0.31 μm; however, after hydrothermal coating, the diameter increased from 0.79 ± 0.31 μm to 2.5 ± 0.9 μm. The contact angle on pristine PU showed 105.53 ± 0.8°, that is, hydrophobicity, which was diminished to 9.3 ± 0.8° by the reorientation of PU with Mg(OH)2, chitosan and Ag NPs, that is, indicative of hydrophilic character. Biomineralization was evaluated by incubating in simulated body fluid, and the EDS and FE‐SEM indicated that composite fibers could induce apatite formation. Cell viability was measured using MTT assay, and cell adhesion/proliferation was confirmed by DAPI staining and FE‐SEM. The composite scaffolds promoted 3T3‐L1 to grow confluently.

Enhancing Mechanical Behavior of Silica and Calcareous Sand through Polyurethane Foam, Nanomaterial, and Fiber

Enhancing Mechanical Behavior of Silica and Calcareous Sand through Polyurethane Foam, Nanomaterial, and Fiber